U.S. Pat. No. 4,313,004 discloses a process for producing bis(aminopropyl)aliphatic glycols through a two step process comprising a first step of reacting acrylonitrile with an aliphatic glycol and then reducing the nitrile group by contacting the cyanoglycol with hydrogen in the presence of a hydrogenation catalyst. In this patent it is reported that various side reactions occur during the hydrogenation step and the extent of byproduct formation is increased where residual acrylonitrile is present. For example, cyanoalkylated glycols may undergo cleavage to form undesired glycols, amino alcohols, polyamines and impurities or the acrylonitrile may react with the amine generated in the reduction, thereby contaminating the reaction product and presenting a separation problem.
U.S. Pat. No. 3,799,986 discloses a process for preparing amines reacting an olefinic nitrile, such as acrylonitrile, with various polyhydroxy compounds followed by hydrogenation. In this process the olefinic nitrile is reacted with the polyhydroxy compound typically in stoichiometric proportions although excess of either can be utilized. After the condensation is completed, the olefinic nitrile is removed under reduced pressure. The patentees point out that it is sometimes difficult to remove the olefinic nitrile because of a tendency to polymerize and the polymerized nitrile impurity in the cyanoalkylated product may poison the hydrogenation catalyst during the hydrogenation step. In general the polymerized nitrile is removed by contacting the reaction mixture with solvents selective for the cyanoalkylated polyhydric alcohol reaction product such as saturated aliphatic and cycloaliphatic hydrocarbons. The hydrogenation then is carried out after removal of hydrocarbon solvent, typically in the presence of a tertiary amine or anhydrous ammonia. Ammonia and tertiary amine tend to minimize cleavage of the cyanoalkylated product during hydrogenation to the amine.